Methods for preparing functionalized polyphenylene ether compositions are known in the art. A process which may be used for making a functionalized polyphenylene ether includes dissolving polyphenylene ether powder in toluene and contacting it, for example, with an epoxychlorotriazine such as mesityl glycidyl chlorocyanurate, a phase transfer catalyst, and an aqueous base, and then precipitating it with methanol. However, the above mentioned process is economically less favorable than functionalizing a crude polyphenylene ether process stream.
Polyphenylene ether has been epoxy functionalized through contact with an epoxy chlorotriazine in the presence of a basic reagent under reactive conditions. However, the polyphenylene ether as well as secondary and tertiary amines present in the process stream compete for the chlorotriazine. Therefore, a large stoichiometric excess of chlorotriazine is required, rendering this method of functionalizing polyphenylene ether not optimally efficient.
The present invention provides a method for more efficiently introducing functionality into polyphenylene ethers. The method of the present invention allows a substantial reduction of capping agent necessary to functionalize polyphenylene ether while producing products that are highly reactive and readily convertible under both solution and melt conditions to copolymers of polyphenylene ethers with a wide variety of strongly and weakly nucleophilic polymers, notably polyamides and polyesters such as polybutylene terephthalate. Blends which contain such copolymers have increased ductility and impact strength, particularly when blended with conventional impact modifiers for polyphenylene ethers.
In one of its aspects, the present invention provides a process for capping polyphenylene ether with chlorotriazine in the presence of nucleophilic species which compete with the polyphenylene ether for the capping agent, without using a large excess of capping agent. The preparation of a substituted triazine-capped polyphenylene ether composition includes the following sequential steps:
(a) contacting under reactive conditions at least one polyphenylene ether with an aqueous basic reagent; and
(b) contacting under reactive conditions a composition resulting from step (a) with substituted chlorotriazine.
In a further embodiment the present invention provides a process for capping polyphenylene ether with chlorotriazine by neutralizing a composition resulting from step (b) with gaseous carbon dioxide.